Bearing Capacity for Round Footing Calculator

Bearing Capacity Formula for Round Footing:

\[ q_{round} = (1.3 \times C \times N_c) + (\sigma' \times N_q) + (0.5 \times \gamma \times B \times N_\gamma \times 0.6) \]

Cohesion (C):

Bearing Capacity Factor (Nc):

Effective Surcharge (σ'):

Bearing Capacity Factor (Nq):

Unit Weight of Soil (γ):

Width of Footing (B):

Bearing Capacity Factor (Nγ):

Bearing Capacity (q_round):

1. What is Bearing Capacity for Round Footing?

Definition: The bearing capacity for round footing is the maximum load per unit area that the soil can support without experiencing shear failure when subjected to loads from a round foundation.

Purpose: It helps civil engineers and geotechnical professionals design safe and stable round foundations for structures.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ q_{round} = (1.3 \times C \times N_c) + (\sigma' \times N_q) + (0.5 \times \gamma \times B \times N_\gamma \times 0.6) \]

Where:

\( q_{round} \) — Bearing capacity for round footing (Pascal)
\( C \) — Cohesion of soil (Pascal)
\( N_c \) — Bearing capacity factor dependent on cohesion
\( \sigma' \) — Effective surcharge (Pascal)
\( N_q \) — Bearing capacity factor dependent on surcharge
\( \gamma \) — Unit weight of soil (N/m³)
\( B \) — Width of footing (m)
\( N_\gamma \) — Bearing capacity factor dependent on unit weight

Explanation: The formula accounts for three components of bearing capacity: cohesion, surcharge, and soil weight.

3. Importance of Bearing Capacity Calculation

Details: Proper bearing capacity calculation ensures foundation stability, prevents settlement issues, and maintains structural integrity.

4. Using the Calculator

Tips: Enter all required parameters with their appropriate units. The ±5% indicates the typical accuracy range for these parameters in geotechnical engineering.

5. Frequently Asked Questions (FAQ)

Q1: Why is there a 1.3 factor for cohesion in round footings?
A: The 1.3 factor accounts for the shape effect of round footings on the cohesion component of bearing capacity.

Q2: Why is there a 0.6 factor for the last term?
A: The 0.6 factor accounts for the shape effect of round footings on the soil weight component of bearing capacity.

Q3: How do I determine the bearing capacity factors?
A: Bearing capacity factors are typically determined based on the soil's angle of internal friction using established geotechnical relationships.

Q4: What's a typical range for cohesion values?
A: Cohesion varies widely: clays (10-200 kPa), silts (5-50 kPa), sands (0-10 kPa).

Q5: How does footing width affect bearing capacity?
A: Wider footings generally have higher bearing capacity due to greater soil involvement in resisting loads.